[P-CG19] Planetary Magneto-Ionosphere &Atmosphere

[PCG19-P09] A potential magnetic reconnection signature on the lunar crustal magnetic field: Kaguya low-altitude observations

*Kohei Ogino¹, Yuki Harada¹, Masaki N Nishino², Yoshifumi Saito², Shoichiro Yokota³, Futoshi Takahashi⁴, Hisayoshi Shimizu⁷, Yoshiya Kasahara⁶, Atsushi Kumamoto⁵ (1.Graduate School of Science, Kyoto University, 2.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3.Graduate School of Science, Osaka University, 4.Department of Earth and Planetary Sciences, Kyushu University, 5.Earthquake Research Institute, University of Tokyo, 6.Information Media Center, Kanazawa University, 7.Graduate School of Science, Tohoku University)

Keywords:Moon, Plasma, Magnetic Reconnection, Mini-magnetosphere

The Moon has no global intrinsic magnetic field, while the solar wind interaction with lunar crustal magnetic anomalies (LMAs) forms lunar mini-magnetospheres. Recent ARTEMIS observations and 2D fully kinetic simulations suggested the occurrence of magnetic reconnection on LMAs (Sawyer et al., 2023; Stanier et al., 2024). Since magnetic reconnection plays a fundamental role in the dynamics of space plasma, by changing magnetic field topology and converting magnetic energy into charged particle energy, magnetic reconnection on LMAs could affect the plasma environment around the moon. However, since the vertical spatial scales of LMAs are small, below several tens of kilometers, it is challenging to directly observe the interaction regions from typical nominal altitudes of lunar orbiters (~100 km) and the details of magnetic reconnection on LMAs have not been fully understood. In this study, we analyze low-altitude data of charged particles and electromagnetic fields obtained by Kaguya. We identified a current sheet crossing from magnetic field data as well as simultaneous characteristic energy variations of electrons from the observed electron velocity distribution. As electron-only magnetic reconnection on sub-ion-scale LMAs (Stanier et al., 2024) could be accompanied by electron outflow jets (Phan et al., 2018), we discuss the possibility that the current sheet-crossing event can be an indicator of the occurrence of magnetic reconnection on the LMA.